Nonlinear frequency response curves estimation and stability analysis of randomly excited systems in the subspace framework

In this paper, the periodic solutions of nonlinear mechanical systems are studied starting from the nonlinear state-space model estimated using the nonlinear subspace identification (NSI) technique. In its standard form, NSI needs the input-output data from a nonlinear structure undergoing broadband excitation and requires the prior knowledge of the locations and kind of nonlinearities to be estimated. The method allows the estimation of the nonlinear features of the system and the indirect study of its periodic solutions using a single broadband excitation, without the need of feedback control loops. To this end, the nonlinear frequency response curves of the system are estimated merging the harmonic balance method with the NSI technique and using a continuation approach. Then, a monodromy-based stability analysis is developed in the nonlinear state-space framework to study the stability of the periodic solutions of the system and to track its bifurcations. The method is validated considering conservative nonlinearities on two numerical examples and one experimental application, the latter comprising a double-well oscillator with period-doubling phenomena. The effects of noise and nonlinear modeling errors are also evaluated

Nonlinear Dynamics of a Duffing-Like Negative Stiffness Oscillator: Modeling and Experimental Characterization

In this paper, a negative stiffness oscillator is modelled and tested to exploit its nonlinear dynamical characteristics. The oscillator is part of a device designed to improve the current collection quality in railway overhead contact lines, and it acts like an asymmetric double-well Duffing system. Thus, it exhibits two stable equilibrium positions plus an unstable one, and the oscillations can either be bounded around one stable point (small oscillations) or include all the three positions (large oscillations). Depending on the input amplitude, the oscillator can exhibit linear and nonlinear dynamics and chaotic motion as well. Furthermore, its design is asymmetrical, and this plays a key role in its dynamic response, as the two natural frequencies associated with the two stable positions differ from each other. The first purpose of this study is to understand the dynamical behavior of the system in the case of linear and nonlinear oscillations around the two stable points and in the case of large oscillations associated with a chaotic motion. To accomplish this task, the device is mounted on a shaking table and it is driven with several levels of excitations and with both harmonic and random inputs. Finally, the nonlinear coefficients associated with the nonlinearities of the system are identified from the measured data

LEVELS OF HEAVY METALS IN ITALIAN MARKETED CANNED TUNA

Fish products are essential and irreplaceable components of human diet; nevertheless, they could result in a risk to the health of consumers due to the potential content of some xenobiotics such as heavy metals and persistent organic contaminants (Debeka et al., 2004; Storelli et al., 2005). Constant control network and surveys are valuable tools in order to prevent such risk and to ensure product quality and consumers??? safety. The aim of the current study was to measure the levels of some heavy metals (Hg, Pb, Cd) in samples of marked canned tuna in olive oil. The results showed that levels of Cd and Hg were always within the law limits and, in many samples, below the detection limit. Pb was found in concentrations exceeding the law limits in 9.8% of the analyzed samples. In conclusion, the results of the current study, quite reassuring in terms of food safety, highlighted the need to constantly monitor the levels of some chemical contaminants in fish products such as heavy metals that might endanger the health of the consumers

Age-Related Impairment in Insulin Release The Essential Role of beta(2)-Adrenergic Receptor

In this study, we investigated the significance of β(2)-adrenergic receptor (β(2)AR) in age-related impaired insulin secretion and glucose homeostasis. We characterized the metabolic phenotype of β(2)AR-null C57Bl/6N mice (β(2)AR(-/-)) by performing in vivo and ex vivo experiments. In vitro assays in cultured INS-1E β-cells were carried out in order to clarify the mechanism by which β(2)AR deficiency affects glucose metabolism. Adult β(2)AR(-/-) mice featured glucose intolerance, and pancreatic islets isolated from these animals displayed impaired glucose-induced insulin release, accompanied by reduced expression of peroxisome proliferator-activated receptor (PPAR)γ, pancreatic duodenal homeobox-1 (PDX-1), and GLUT2. Adenovirus-mediated gene transfer of human β(2)AR rescued these defects. Consistent effects were evoked in vitro both upon β(2)AR knockdown and pharmacologic treatment. Interestingly, with aging, wild-type (β(2)AR(+/+)) littermates developed impaired insulin secretion and glucose tolerance. Moreover, islets from 20-month-old β(2)AR(+/+) mice exhibited reduced density of β(2)AR compared with those from younger animals, paralleled by decreased levels of PPARγ, PDX-1, and GLUT2. Overexpression of β(2)AR in aged mice rescued glucose intolerance and insulin release both in vivo and ex vivo, restoring PPARγ/PDX-1/GLUT2 levels. Our data indicate that reduced β(2)AR expression contributes to the age-related decline of glucose tolerance in mice

Heavy Metals in Canned Tuna from Italian Markets

Fish is a good source of nutrients for humans but can pose a risk to human health because of the possible presence of some xenobiotics such as heavy metals and persistent organic contaminants. Constant monitoring is needed to minimize health risks and ensure product quality and consumer safety. The aim of the present study was to use atomic absorption spectrometry to determine the concentrations of some heavy metals (Hg, Pb, and Cd) in tuna packaged in different kinds of packages (cans or glass) in various countries (Italy and elsewhere). Concentrations of Cd and Hg were within the limits set by European Commission Regulation (EC) No 1881/2006 and in many samples were below the detection limit. Pb concentrations exceeded European limits in 9.8% of the analyzed samples. These results are reassuring in terms of food safety but highlighted the need to constantly monitor the concentrations of heavy metals in fish products that could endanger consumer health

Impact of Immersive Training on Senior Chemical Engineering Students\u27 Prioritization of Process Safety Decision Criteria

Every year new safety features and regulations are employed within the process industry to reduce risks associated with operations. Despite these advancements chemical plants remain hazardous places, and the role of the engineer will always involve risk mitigation through real time decision making. Results from a previous study by Kongsvik et al., 2015 indicated that there were three types of decisions in major chemical plants: strategic decisions, operational decisions, and instantaneous decisions. The study showed the importance for improving upon engineers’ operational and instantaneous choices when tasked with quick solutions in the workforce. In this research study, we dive deeper to understand how senior chemical engineering students’ prioritize components of decision making such as budget, productivity, relationships, safety, and time, and how this prioritization may change as a result of participation in a digital immersive training environment called Contents Under Pressure. More specifically, we seek to address the following two research questions: (1) How do senior chemical engineering students prioritize safety in comparison to criteria such as budget, personal relationships, plant productivity, and time in a process safety context, and (2) How does senior chemical engineering students’ prioritization of decision making criteria (budget, personal relationships, plant productivity, safety, and time) change after exposure to a virtual process safety decision making environment? As part of this study, 187 senior chemical engineering students from three separate institutions completed a pre- and post-reflection survey around their engagement with Contents Under Pressure and asked them to rank their prioritizations of budget, productivity, relationships, safety, and time. Data was analyzed using descriptive statistics, and Friedman and Wilcoxon-sign-rank post hoc analyses were completed to determine any statistical differences between the rankings of decision making factors before and after engagement with Contents Under Pressure. Simulating process safety decision making with interactive educational supports may increase students’ understanding of genuine workplace environments and factors that contribute to process safety, without the real world hazards that result from poor decision making. By understanding how students prioritize these factors, chemical engineering curricula can be adapted to focus on the areas of process safety decision making where students need the largest improvement, thereby better preparing them to enter the engineering workforce

SIRT3 Modulates Endothelial Mitochondrial Redox State during Insulin Resistance

Emerging evidence indicates that defects in sirtuin signaling contribute to impaired glucose and lipid metabolism, resulting in insulin resistance (IR) and endothelial dysfunction. Here, we examined the effects of palmitic acid (PA) treatment on mitochondrial sirtuins (SIRT2, SIRT3, SIRT4, and SIRT5) and oxidative homeostasis in human endothelial cells (TeloHAEC). Results showed that treatment for 48 h with PA (0.5 mM) impaired cell viability, induced loss of insulin signaling, imbalanced the oxidative status (p < 0.001), and caused negative modulation of sirtuin protein and mRNA expression, with a predominant effect on SIRT3 (p < 0.001). Restoration of SIRT3 levels by mimic transfection (SIRT3+) suppressed the PA-induced autophagy (mimic NC+PA) (p < 0.01), inflammation, and pyroptosis (p < 0.01) mediated by the NLRP3/caspase-1 axis. Moreover, the unbalanced endothelial redox state induced by PA was counteracted by the antioxidant δ-valerobetaine (δVB), which was able to upregulate protein and mRNA expression of sirtuins, reduce reactive oxygen species (ROS) accumulation, and decrease cell death. Overall, results support the central role of SIRT3 in maintaining the endothelial redox homeostasis under IR and unveil the potential of the antioxidant δVB in enhancing the defense against IR-related injuries

Relativistic Structure of the Nucleon Self-Energy in Asymmetric Nuclei

The Dirac structure of the nucleon self-energy in asymmetric nuclear matter cannot reliably be deduced from the momentum dependence of the single-particle energies. It is demonstrated that such attempts yield an isospin dependence with even a wrong sign. Relativistic studies of finite nuclei have been based on such studies of asymmetric nuclear matter. The effects of these isospin components on the results for finite nuclei are investigated.Comment: 9 pages, Latex 4 figures include

The Church of S. Maria Delle Palate in Tusa (Messina, Italy): Digitization and Diagnostics for a New Model of Enjoyment

Cultural places represent the tangible part of the identity and historical heritage of a civilization as well as an extraordinary driving force for the economic development of a country. Within its huge asset, Italy counts a wide number of archaeological sites and monuments which, despite their cultural value, are totally cut off from the most important cultural routes. This paper aims to demonstrate how specific actions of digitization can contribute to valorize (restoring a cultural value) ‘marginal’ landmarks, promoting their knowledge and inclusion. The case study described is represented by the Church of “Santa Maria delle Palate”, located inside the well-known Archaeological Park of Halaesa Arconidea (Tusa, ME). The church, built in 1551 and subject to several renovations throughout the centuries, has been investigated as part of an interdisciplinary training and skill transfer project carried out by a CNR-IPCF research team. During the activities, the group of trainees approached a multi-analytic method for the study of many Sicilian places using different techniques such as laser scanning, photogrammetry, thermography and spectroscopy and collecting a large amount of information and data. In 2019, the building in question was the object of a complete architectural survey in order to obtain an accurate digital replica; moreover, the wall painting representing St. Francis, preserved in the southern nave, was investigated through non-invasive investigations (IR-imaging, XRF and Raman spectrometry) with the intention of collecting information about its state of preservation and nature of pigments used and help the restoration work, which would have been carried out in the following months. The result of the work is a combined “digital archive” useful not only for the purposes of conservation, monitoring and dissemination, but as a container of information enjoyable at different levels of depth. In addition to the scientific outcomes achieved for the study of the painting, relevant from the historical and artistic point of view, we must underline the importance of the work for the implementation of a web-based platform where expert and inexpert users can virtually access the church virtual tour and search for specialized contents (e.g., measures, analyzes results). Media such as this are finally demonstrated to be able to promote the inclusion (e.g., for people unable to reach the place or with reducing mobility) and accessibility to cultural places during ordinary (maintenance, closure) or extraordinary events (pandemic)

Pimavanserin and Lorcaserin Attenuate Measures of Binge Eating in Male Sprague-Dawley Rats

Binge eating disorder (BED) is characterized by dysregulated feeding and reward-related processes, and treatment is often challenged by limited therapeutic options. The serotonin (5-HT) 5-HT2A receptor (5-HT2AR) and 5-HT2CR are implicated in both feeding-related and reward-related behaviors and are thus poised to regulate BED-related behaviors. The purpose of this study was to assess the efficacy of the FDA-approved medications pimavanserin, a 5-HT2AR antagonist/inverse agonist, and lorcaserin, a 5-HT2CR agonist, in a rodent model of binge eating. The effects of pimavanserin (0.3–3.0 mg/kg), lorcaserin (0.25–1.0 mg/kg), and the lowest effective dose of pimavanserin (0.3 mg/kg) plus lorcaserin (1.0 mg/kg) were tested in a high-fat food (HFF) intermittent access binge eating model in adult male Sprague-Dawley rats (n = 64). We assessed three measures related to binge eating – binge episode occurrence, binge intake, and weight gain associated with HFF access. Pimavanserin decreased binge intake and weight gain associated with HFF access, but did not prevent binge episode occurrence. Lorcaserin decreased binge intake, but did not prevent binge episode occurrence or weight gain associated with HFF access. Combined pimavanserin plus lorcaserin prevented binge episode occurrence in addition to decreasing binge intake and weight gain associated with HFF access. These preclinical findings in male rats suggest that pimavanserin and lorcaserin may be effective in treating patients with BED. Our studies further indicate that administration of one or both drugs may be more effective in certain sub-populations of patients with BED because of the unique profile each treatment elicits. These data support future assessment in clinical populations with BED